Field of the Invention
The invention lies in the automotive technology field. More specifically, the invention relates to a device for sensing an object or a person in the interior of a vehicle. A sensor is provided for this purpose. The device includes an attachment member with which the device is attached to the vehicle in a given position and with a given orientation for the sensor. The invention also pertains to a related operating method for a device for sensing an object or a person in the interior of a vehicle.
Persons who are displaced far forward in the direction of the dashboard--such as children in rearward facing child or infant seats that are placed on the front passenger seat--are subjected to the hazard, during the operation of a motor vehicle provided with an airbag, of suffering injuries as result of the inflation impact of the airbag in the event of an accident. Modern occupant protection control systems aim at switching off the airbag in such situations or inflating it with reduced force and speed in order to avoid the risk of injury to a vehicle occupant. It is thus necessary to determine the position of the vehicle occupant in the vehicle. In order to determine the position of the vehicle occupant, use is preferably made of contactless, optical sensors.
European published patent application No. 0 669 227 A1 discloses a device for the contactless detection of an object or of a person in the interior of a vehicle. There, the vehicle seat is irradiated by a number of LEDs. The beams which are reflected from the seat or a person or an object on the vehicle seat are registered by a photodetector field.
The location at which such a device is installed in the vehicle, for example, on the A pillar, on the B pillar, or on the roof lining, integrated with the interior lighting if appropriate, can generally be specified by the manufacturer of the vehicle only with a tolerance of approximately .+-.5% with respect to a fixed point in the vehicle. Manufacture-related tolerance chains in the bodywork of the vehicle do not permit the place of installation to be determined more precisely. However, a local tolerance of 5% already results, for a scanning device using optical scanning, in an angular deviation of the beam path of a maximum of 18.degree. with respect to a fixed object that is to be scanned. In the case of an assumed function area of the device--also referred to as range--of one meter--the measuring point can be displaced by approximately 30 cm. Such a tolerance in the sensing of objects or persons for the purpose of switching off an airbag or the appropriate metering of an airbag is not acceptable for safety reasons. Hazardous situations are not detected owing to such an indeterminate installation position of the device, or are assessed incorrectly because, although the device is operating without faults per se, it is not monitoring the intended area owing to its incorrect installation position.